Whitney Houston was underwater and apparently unconscious when she was pulled from a Beverly Hills hotel bath - and she had prescription drugs in her room, authorities have said.

Two days after her death, Houston's body was taken to a small, Los Angeles-area airport to be flown to her home state of New Jersey, where her family was making arrangements for a funeral at the end of the week.

An autopsy was done on Sunday and authorities said there were no indications of foul play and no obvious signs of trauma on Houston's body. However it could be weeks before the coroner's office completes toxicology tests to establish her cause of death.

The 48-year-old singer had struggled for years with cocaine, cannabis and pills, and her behaviour had become erratic.

She was found on Saturday at the Beverly Hilton Hotel by a member of her staff at about 3.30pm, just hours before she was supposed to appear at a pre-Grammy Awards gala, police officer Mark Rosen said.

She was pulled from the bath by members of her staff and hotel security was promptly notified, Mr Rosen said. She was pronounced dead about a half-hour later.

"As of right now, it's not a criminal investigation," he said. "We have concluded our portion of the investigation at the hotel."

Los Angeles coroner's assistant chief Ed Winter said there were bottles of prescription medicine in the room. He said: "There weren't a lot of prescription bottles. You probably have just as many prescription bottles in your medicine cabinet."

The coroner's office released the body to the family on Monday morning. Later, a police convoy accompanied two vehicles into a Van Nuys Airport hangar, and a private jet rolled out of the hangar and later took off.

Two people who spoke to Houston's family said the singer would be taken to New Jersey. They said he relatives had raised the possibility of a wake on Thursday and a funeral the following day at Newark's Prudential Centre, an arena that can seat about 18,000 people.